Felt and Tarrant Comptometer

Felt and Tarrant Comptometer

Dorr E. Felt (1862-1930) achieved the technological breakthrough of a key-driven adding machine. The Comptometer's key set the number to be added or subtracted, and provided the power for performing the operation. Both fast and reliable, the machine was used in both business and science. It not only added and subtracted but also performed multiplication and division.